Even when we were reading Asimov back when he was writing it we all knew that he lacked depth of characterisation. However, we loved him for the plots and the ideas and the way his stories leapt off the page.

There's more than one route to greatness, and as others have said many have built on what he did to climb higher and further.

Graham

Absolutely. Asimov's characters are two-dimensional, cardboard characters, but for all of that he is unquestionably one of the great SF authors. Why? Because of his ideas and his plots. Asimov invented the "galaxy-spanning galactic empire" depicted in his "Foundation" novels; the sweep of his imagination surpassed that of almost any other author of his day.